The present invention relates to an electric fuel injection pump governor for a fuel injection pump of an internal combustion engine of compressed ignition type (Diesel engine), in which a value corresponding to a target of the amount of fuel injection is calculated by searching a predetermined memory map thereby to correct the actual amount of injection to the target.
In conventional methods of controlling the amount of fuel injection of the distribution type fuel injection pump of the Diesel engine, the centrifugal force generated by the flyweight driven by the governor drive gear provides a basis with which a variety of spring levers are combined in a complicated manner thereby to generate a fuel injection amount pattern (what is called the governor pattern). This is what is called a mechanical governor. The governor patterns generated by the mechanical governor are basically of two types, the all speed type governor pattern and the minimum-maximum speed type governor pattern. The all-speed type governor pattern has the advantage that the control may be effected to maintain a fixed rotational speed at any given engine speed depending on the characteristics thereof. In the case where this type of governor pattern is used for the automobile engine, however, the driver feels that the acceleration characteristic of the automobile is deteriorated. On the other hand, the shortcoming of the minimum-maximum speed type governor pattern is that in spite of the satisfactory acceleration characteristic felt by the driver, it is difficult for the engine rotation speed to be maintained constant against load changes.
In view of these facts, the all-speed type governor pattern superior in the stability of the engine rotational speed is suitable in the low speed range, namely, in or about the idling speed, while the minimum-maximum speed type governor superior in acceleration characteristic is a choice for the engine being accelerated or under a load. It is therefore desirable to change the governor pattern according to the engine rotation speeds, and in order to achieve this, the governor pattern is generated by use of various springs and levers in usual arrangements. The mechanical governor, which uses various types of springs and levers, is large in weight, low in accuracy and too complicated to receive satisfactory maintenance. In addition, if the error of the amount of injection encountered by the distribution type of the fuel injection pump at the same spill ring position depending on the engine rotational speed is to be corrected, a more complicated device is required, resulting in an increased volume, weight and cost.